package network3;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TcpEchoServer {
    private ServerSocket serverSocket = null;

    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }

    public void start() throws IOException {
        System.out.println("服务器启动：");
        ExecutorService threadPool = Executors.newCachedThreadPool();
        while (true) {
            Socket clientSocket = serverSocket.accept();
            threadPool.submit(() -> {
               processConnection(clientSocket);
            });
        }
    }

    private void processConnection(Socket clientSocket) {
        System.out.printf("[%s : %d] 客户端上线！\n", clientSocket.getInetAddress().toString(),
                clientSocket.getPort());
        try(InputStream inputStream = clientSocket.getInputStream();
            OutputStream outputStream = clientSocket.getOutputStream()) {
            while (true) {
                // 1. 读取请求
                Scanner scan = new Scanner(inputStream);
                if (!scan.hasNext()) {
                    System.out.printf("[%s : %d] 客户端下线\n", clientSocket.getInetAddress().toString(),
                            clientSocket.getPort());
                    break;
                }
                String request = scan.next();
                // 2. 根据请求计算响应
                String response = process(request);
                // 3. 返回响应结果
                PrintWriter printWriter = new PrintWriter(outputStream);
                printWriter.println(response);
                printWriter.flush();
                System.out.printf("[%s : %d req: %s; resp: %s]\n", clientSocket.getInetAddress().toString(),
                        clientSocket.getPort(), request, response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer tcpEchoServer = new TcpEchoServer(9090);
        tcpEchoServer.start();
    }
}
